FBI and DEA agents have disrupted a plot to commit a “significant terrorist act in the United States” tied to Iran, federal officials told ABC News today.

The officials said the plot included the assassination of the Saudi Arabian ambassador to the United States, Adel Al-Jubeir, with a bomb and subsequent bomb attacks on the Saudi and Israeli embassies in Washington, D.C. Bombings of the Saudi and Israeli embassies in Buenos Aires, Argentina, were also discussed, according to the U.S. officials.

U.S. Attorney General Eric Holder said in an announcement today that the plan was “conceived, sponsored and was directed from Iran” by a faction of the government and called it a “flagrant” violation of U.S. and international law.

“The U.S. is committed to holding Iran accountable for its actions,” Holder said. He said the White House will be meeting with federal agencies before announcing “further action” in regards to Iran.

The criminal complaint alleges that, from the spring of 2011 to October 2011, Arbabsiar and his Iran-based co-conspirators, including Shakuri of the Qods Force, have been plotting the murder of the Saudi Ambassador to the United States. In furtherance of this conspiracy, Arbabsiar allegedly met on a number of occasions in Mexico with a DEA confidential source (CS-1) who has posed as an associate of a violent international drug trafficking cartel. According to the complaint, Arbabsiar arranged to hire CS-1 and CS-1’s purported accomplices to murder the Ambassador, and Shakuri and other Iran-based co-conspirators were aware of and approved the plan. With Shakuri’s approval, Arbabsiar has allegedly caused approximately $100,000 to be wired into a bank account in the United States as a down payment to CS-1 for the anticipated killing of the Ambassador, which was to take place in the United States.

According to the criminal complaint, the IRCG is an arm of the Iranian military that is composed of a number of branches, one of which is the Qods Force. The Qods Force conducts sensitive covert operations abroad, including terrorist attacks, assassinations and kidnappings, and is believed to sponsor attacks against Coalition Forces in Iraq. In October 2007, the U.S. Treasury Department designated the Qods Force for providing material support to the Taliban and other terrorist organizations.

The complaint alleges that Arbabsiar met with CS-1 in Mexico on May 24, 2011, where Arbabsiar inquired as to CS-1’s knowledge with respect to explosives and explained that he was interested in, among other things, attacking an embassy of Saudi Arabia. In response, CS-1 allegedly indicated that he was knowledgeable with respect to C-4 explosives. In June and July 2011, the complaint alleges, Arbabsiar returned to Mexico and held additional meetings with CS-1, where Arbabsiar explained that his associates in Iran had discussed a number of violent missions for CS-1 and his associates to perform, including the murder of the Ambassador.

At a press conference this afternoon, Holder ducked questions about the Fast and Felonious scandal.

Congressional investigators probing the failed anti-gunrunning operation Fast and Furious are sending a new subpoena to Attorney General Eric Holder — seeking communications from about a dozen top Justice Department officials, including Holder; his chief of staff, Gary Grindler; and the head of the department’s criminal division, Lanny Breuer, Fox News has learned.

The subpoena, which could be filed as early as Tuesday, will focus on the Justice Department. The first and only subpoena issued so far dealt with the Bureau of Alcohol, Tobacco, Firearms and Explosives. That subpoena was issued back in March.

Congressional investigators probing the failed anti-gunrunning operation Fast and Furious are sending a new subpoena to Attorney General Eric Holder.

In the new subpoena, congressional investigators will apparently demand information regarding the investigation into the death of U.S. Border Patrol agent Brian Terry. Two guns found at Terry’s crime scene were linked to the failed operation that allowed more than 2,000 weapons to “walk.”

The subpoena is expected to ask for correspondence that Justice Department officials had with the White House about the gun trafficking operation, as well as what information was shared by Justice officials in Mexico.